Stoker control



Patented Apr. 19, 1921.

5 SHEETSSHEET 1.

H. T. HERB.

STOKER CONTROL.

APPLICATION FILED NOV:6,1915. 1375,2509

IN VE N TOR.

H/S ATTORNEY IN FACT WITNESSES:

H. T. HERR.

STOKER CONTROL.

APPLICATION FILED NOV= 6, 1915.

1,375,250, Patented Apr. 19, 1921.

5 SHEETS-SHEET 2. 67

\ IN vE/vToR';

BY m... M

HIS ATTORNEY IN FACT H. T. HERR.

STOKER CONTROL.

APPLICATION FILED NOV 6, 1915.

1,375,250, Patented Apr. 19,1921.

5 SHEETSSHEET 4.

cuk

Imrl

H. T. HERR.

STOKER CONTROL.

APPLICATION FILED NOV. 6, 1915.

Patented Apr. 19, 1921.

5 SHEETS-SHEET 5.

INVENTOR.

HIS ATTORNEY IN FACT tion to variations in the pressure 0 um'rsn srA'n-zsrarela'r omce.

nnnnnnr 1*. 11mm, or rrmszaunen, PENNSYLVANIA, assxsNoa r0 wnsrrNci-ronsn ELECTRIC a MANUFACTURING COMPANY, a CORPORATION or PENNSYLVANIAEL- sro'xnn coNrnoL.

specliloation'ot Letterslfatent. p t a 9 1 Application mednovember e, 1915. Serial'li'o. 00,013.,

To all whom it may concern Be it known that I, HERBERT T. Hmim a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have made ,a

new and useful Invention in Stoker Control,

of which the following is a specification.

This invention relates to. automatic control mechanism and has for a specialobject to produce a. control mechanism which will automatically. control the operation of a; mechanical stoker by varying the fuel and A further and more, general object of the "invention is to produce a new and improved control mechanism capable of independently controlling a number of separate mechanisms or devices in response to variations in the'result accomplished by the cooperation of all the devices. I

A still further object o'fthe invention is to produce a new and improved control mechanism, which is responsive in operasteam supplied by a steam generator, and which controls the operation of a mechanical Stoker operating in conjunction with the steam generator.

These and other objects, WhlCh w1ll be made apparent throughout the further descriptionof the invention, are accomplished by means of apparatus-embodying the features herein described and illustrated in the drawings accompanying and forming a part hereof. I

In the drawings: Figure 1 is a more or less diagrammatic view of ap" aratus em bodying my invention, portions eing shown in section for convenience of illustration.

Fig. 2 is a vertical sectional view of 'a control mechanism for a blower or fan, which'mechanism forms a detail of .the apparatus illustratedgand a part of my present invention. .1

Fig. 3 is a sectional; view of a pressure responsive device forming a detail oflthe-"pres ent invention, an'diwhich is illustrated on a reduced scale in Fig.1.

for the device illustrated in Fig. 3. j

the

operating mechanism 12.

Fig. 5 is avertical sectional view of a relay mechanism which forms a part of the present invention and which may be sub stituted for the relay mechanism shown in 1. 1 1g. 6 is a sectional view taken at right angles to the view illustrated in Fig. 5, and 1llustrates a portion of the mechanism there illustrated.

I Fig. 7 is a sectional view of a governor WhlCh forms a detail of the present invention.

Fig. 8 is a detailed sectional view of the control valve of the relay mechanism 'ill'us trated 1n Fig. 1.

The apparatus illustrated as an fifnhodiment of my invention is adapted to control the operation of one or more mechanical stokers in response to variations in the pressure of the steam delivered by one or more steam generators or boilers operating-in con-f junction with the Stoker or stokers. It in-f cludesa pressure responsive device which is] responsive in operation to the pressure of the steam delivered by the generator or generators, or to the pressure of the steam in a steam supply pipe and operates through the agency of a relay mechanism to increase the actuating pressure delivered to one or more control mechanisms as the steam pressure falls off and vise versa, to decrease the actuating pressure delivered to the control mechanisms as the steam pressure increases.

'As illustrated, the control mechanisms are adapted to control the operation of fans or blowers delivering forced draft to one or morefurnaces and the operation ofan engine or motor which drives the fuel delivery mechanisms of the mechanical stokers with -which the furnaces areequipped. It will,

of course, be understood that one or more of the control mechanismsmay be employed to actuate dampers, etc., and that conse-'. quently the air supply to the furnace or furnaces may be controlled in installations employing natural draft as well as in installations employing forced draft.

Referring to Fig. 1, the apparatus includes a pressure responsive device 10, which communicates with a steam supply pipe 11', and is adapted to control the -de livery of fluid under' pressure to a relay As illustrated,

fluid under pressure is delivered by the device 10 to the mechanism 12 from a compressor 13, which is preferably adapted to supply airunder a constant and determined pressure. While I have illustrated theapparatus as including anair compressor, it will be understood that any fluid under pressure may be employed and that I employ the term fluid in its broad sense to include liquids as well as gases. The mechanism 12 15 which delivers air to the furnace or.

furnaces 15 operating in conjunction with;

. the steam generator or. generators 15 supplying steam to the steam pipe 11, and one of these mechanisms is illustrated in Fig. 2. The control mechanism 16 consists of a pressure controlled governor, illustrated in detail in Fig. 7, and adapted to control the operation of a stoker engine 19, which drives- 10 includes a casing. provided at one end the mechanical stoker or stokers 19 operating in conjunction with the steam generator or generators supplying steam to the'pi e 11. As illustrated, the engine 19' drives t e stoker or stokers 19 b means of a lay shaft 19 ina manner well own to those skilled in the art.

As illustrated in Figs. 1 and -3,the device'- with a steam chamber 20, which communicates with the pipe 11 by means of a pipe 21. the illustration in Fig. 1 is diagrammatic and that the pipe 21 would, in large stoker installations, communicate directly with the Y steam header receiving steam from all of the generators included in the unit to 'be coni I v between oneend of the casing and a flexible trolled. The steam chamber 20 is located wall or diaphragm 22 against the outer face 'of which, a.-plunger 23 is held by means of a coiled spring 24. As illustrated, the

spring operates between the plunger and an adjustable spring 'seat 25, which is screwed ,into the casing and is capable of being 2 turned to. different posltions for the purpose of varying the tension of the spring. The plunger is provided with a stem 26, which abuts a ainst a flexible wall or diaphragm 27 forming one wall of fluid delivery chamber- 28. The plunger .23 andits stem-26 are so proportioned thatj-a movement of either of the diaphragms toward the plunger will laterally displace the other dia hragm. A spring seated valve 29 is locate within thev casing and controls the'delivery of fluid,

the chamber 28; This valve is -so construct- It will, of course,-be understood that.

I ne'raaae ed that it cotiperates with the diaphragm 27 in controlling communication between the chamber 28 and the atmosphere. In theillustration this is' accomplished by providing the valve with a hollow stem 31, which forms a means of communication between the chamber 28 and the atmosphere and is adapted to be engaged by the diaphragm 27 both for the purpose of closing communication between the chamber and the atmosphere and of lifting the valve from its seat and establishing communication between the chamber and the. pipe 30. The chamber 28 is provided with a delivery port which commumcates through pipe 32w1th the relay operating mechanism 12' and is therefore adapted to either deliver air under pressure to the mechanism 12 or to exhaust the mechanism by establishing communication between it and the atmosphere.

7 As illustrated, the mechanism 12 includes a casing 33, which incloses a plunger 34 and with the lower end of which and below the plunger, the pipe 32 communicates. The; plunger is provided with a stem 35,

equipped at its outer end with a rack 36 A" coiled spring 37 surrounds the stem 35 and operates between one end of the casing 33 and the plunger 34 to oppose movements of the plunger in response to air pressure delivered through'the pipe 32. Movements of the plunger, in response either to air or sprmg'pressure, actuate a cam 38 through the agency of a gear 39 mounted on a cam shaft 41 and meshing with the'rack 36. The cam shaft 41 is diagrammatically shown in perspective for the purpose of simplifying the illustration, and as illustrated in Fig. 1, the mechanism 12 is supposed to be located behind and to one side of the relay mechanism 14. The relay; mechanism is clearly described and illustrated in my Patent'No.

1,209,579, granted December 19, 1916, and entitled-Fluid distributer, which was filed by me on May 1, 1913; consequently a brief no description only will be given,

The cam 38 forms a part of the relay mechanism and is adapted 'to control the operation of a tubular or hollow rod' 39 which in effect forms an air delivery valve controlling the delivery of air to and the discharge of air from a "central pressure chamber 30 of that mechanism,

, The mechanism 14 also includes twoend chambers, 11' and 12'; thev former of which is inclosed between an end wall of the mech-v anism casingand a diaphragm 13, and the] latter of which is inclosedbetween the other end wall of the casing and a diaphragm 14*. The diaphragm 13 controls the operation of a discharge valve 24 adapted to place the chamber 11' in direct communication with the atmosphere; and the dia hragm hereinafter termed air, from a pipe 30 to l 14: controls the operation of a va ve 16,

- the chamber 12' and conse uent y to the chamber 11', since these chain ers communicate with each other through the passage P which is clearly shown at 56 in Patent No. 1,209,579. The passage 69 receives air under pressure from the compressor 13 through the pipe 30 and a branch pipe 56. A branch passage 29 delivers air under pressure to the hollow rod 39 having one end closed by a plug 40 adapted to bear against the cam 38. The hollow rod 39 is provided with openings 41 always registering with the inlet passage 29 so that air maypass from the passage 29 into the rod. The hollow rod 39 is normally closed at the end farthest from the point 40 by a piston valve 42 which slides in a piston 43 which is provided with openings 44 adapted to register with openings 45 in the tube. The valve 42 for the hollow rod 39 is adapted to cover a central port 46 in the piston through which air may exhaust and pass out through the ports 47 and 48 to the atmosphere. The valve v42 is provided witha in or projection 49 around which is a coil spring 50, one endof which bears against the valve 42 and the other against a spring seat 51 in the piston 43. One end of the piston 43 is provided with a point bearing 52 which seats against a spring pressed seat 53. One end of a coil spring 54 abuts against seat 53 and the other end bears against ascrew plug 55, being adapted to be used as an adjustment for varying the tension of the sprin 54. x

The arrangement is such that as the cam 38 is turned, in response to the decreasing air pressure within the mechanism 12, it forces the tubular valve 39 inwardly, thereby uncovering the'ports 45 and delivering air under pressure to the central chamber 30 As this pressure builds up, the plun ger 43', moving in response to it and in opposition to the s ring 54, closes the ports 45, thereby establish within the chamber 30 for each position of the cam 38 and consequently bf the valve 39. 'As is described in said prior patent, the plunger also operates to discharge air from the chamber 30 through a port 48, when the pressure exceeds that for which the valve 39 is set. The pressure in the chamber 30*- operating upon the diaphragms 13 and 14 presses the valve 24 against its seat and opens the valve 16", thereby admitting high ressure air to the chambers 12' and 11'. The pressures in these chambers will therefore build up until equilibrium is established between them and the chamber 30, at which time the valve 16 will close. A further building up of the pressures within the chambers 11 and 12' will cause the diaphragm 13 to open the valve 24 and discharge excess pressure to the atmosphere.

ing a determined pressure In this way the relay mechanism 14 adjusts the pressure delivered-to the control mechanisms in accordance-with variations n steam pressures; it may be so adjusted that the air ressure delivered b ,it will vary n any esired ratio with re ation to variations in the steam pressure encountered by the device 10.

Itwill, of course, be apparent that a receiver and-a constant pressure valve may be located between the compressor 13 and the piping 30, wh1ch delivers air under pressure to the device 10 and the mechanism 14.

One of the control devices 15 is illustrated in Fig. 2 on an enlarged scale and is adapted to control the steam elivery valve of an engine or turbine 15 driving one of the fans or blowers supplym forced draft to one of the furnaces include in th unit controlled. As illustrated, the mechanism 15 includes a plunger 57, which is exposed on one side to the air pressure, delivered by the relay mechanism 14, through a branch pipe 58, 4 and which is operatively connected to a diahragm 59 located within a pressure chamer formed within the casin of the mechamm. The diaphragm 59 divides the pressure chamber into a compartment 60, open to the atmospher through a port 61, and a compartment 62, which communicates with the delivery port of the blower controlled,

through apipe or passage 63, and is consequent y exposed to the air pressure delivered by the "blower. The stem of the plunger 57 projects through the diaphragm 59 and is provided with an extension 64, on which the throttle valv 65 of the engine, driving the controlled blower, is mounted. As illustrated, the valve 65 IS a balanced valve and controls communication between a steam inlet pipe 67 and a steam delivery pipe 66, which communicates 'with the blower driving engine. The air pressure delivered by the mechanism 14 operating on the plunger 57 tends to further open the valve 65 and to thereby deliver additional steam to the drivin engine. This pressure on the plunger is owever opposed b the pressure delivered by the controlled blbwer and operating on the diaphragm 59 and consequently th diaphragm will tend to close the valve as the output of the blower is increased. In this way the valve 65 will controlthe operation of the blower in response to the air pressure delivered through the branch pipe 58, and the output of the blower will vary in response to variations in the pressiige of the steam delivered to the device In the drawings I have shown a coiled spring 68 arranged to supplement the air pressure delivered to the plunger 57. This an initial pressure on the plunger which is will be just sufiicient to keep t independent of the air pressure delivered through branch pipe 58. In this Wit? the valve 65 is maintained open and the b ower is kept in operation even though the steam pressure delivered to the device 10 is \such that no air under pressure is delivered to the control mechanism by the relay mechanism 14. This spring may of course, be so adjusted that the supply of steam dellvered to the engine or turbine drivlng the blower e blower 1n 0 eration, and, as above described, the diaplunger for counteracting or opposing the cellitrifugal force exerted by the governor ba Is.

The admission valve (not shown) of the stoker engine 19is actuated by means of a lever 70, provided with a control spring 71 which, as illustrated, normally tends to open the valve and to hold the free end of the lever against a governor spindle 72. A pressure actuated plunger 73 is mounted on the spindle 72 and operates within a cylinder 7 4,

z A spring 75 is located within the cylinder 74 so 'as to oppose the motion of the piston in response to fluid pressure and so as to oppose the valve openmg pull of the spring 71 on the lever 70. This s ring is preferably so pro ortioned that it W111 prevent the governor rom hunting by imposing a, pressure on it whichwill gradually increase as the governor balls move outwardly. The governor balls 76 are mounted on linkszin the usual manner and are adapted to oppose the pressure of the air acting on the plunger .7 3 and to close the valve of the en 'ne 19 as the engines speed increasesl As is illustrated,- the cylinder 74 is mounted on a driven shaft of the engine and one set of the governor ball links are pivoted on it. The other set of links are pivoted on pins which are carried by the plunger 73 and project throu h slotted openings in the cylinder. Air un er pressure is delivered to the cylinder 74 through the hollow interior of the governor spindle 72, which is provided-with a telescoping delivery pipe 77 connected to and receiving air under pressure froma branch pipe 78 which communicates with the air delivery pipe 17. With this arrangement the spring 75 normally presses the governor spindle 72 against the thrust bearing 79,

parasite with whichthe free end of the lever 7Q is provided, and air under pressure, entering the cylinder, varies the efl'ectiveness of the 1 is free to move the lever to open adjustment of the governor and consequently vary the speed of the engine 19.

The operation of the apparatus is as fol-' lowszAs the steam pressure in the pipe 11 decreases below the desired or determined pressure or that for which the spring 24 of the device 10 is adjusted, the diaphragm 22, moving in response" to the pressure of the plunger 23, permits the diaphragm 27 to move in response to the pressure of the air in the chamber 28 and away from the inner end of the valve stem 31 of the valve 29. This insures the closing of the valve 29 and places the delivery-chamber 28 in communication with the atmosphere through the hollow stem 31. The chamber 28 and consequently relay control device 12 are thereby exhausted and consequently the plunger 34 moves, in response to the pressure of the sprmg 37, and shifts the position of the cam 38 so as to introduce air under pressure to the central chamber 30 of the mechanism 14. As has been described, the degree of pressure admitted to the chamber 30 is determined by the position of the tubularthe positionv valve 39* and consequently b of the actuating plunger 34. The admission of pressure within the central chamber 30 causes a corresponding pressure tobe delivered to the chambers 11' and 12' of the mechanism 14 and consequently to each of the controlling mechanisms 15 and '16. It has already been described that an increase in the pressure delivered to the plungers 57 of the mechanisms 15 will open the steam delivery valves of the engine drivin the blows ers and increase the output of t e blowers.

l [t has also been described that an' increase 1n the pressure delivered to the piston 73, of

the control mechanism 16, will cause the engine 19 to speed up by increasing the limits between which the engine governor operates.

As the steam pressure builds u trol mechanism the dia hragm 22 of the device 10 moves first to e l the valve stem 31 by forcing the diaphragm 27 against it and then, continuingits move- -ment, opens the valve 29. The opening of the spring 24 and tends to move the plunger in response to the operation of the orgamzed con- .120 ose the inner endof 23 downwardly or in opposition to the steam prewlreexerted on the diaphragm 22. Consequently, when the pressure w thin the chamber 28 and the pressure of the spring 7 tinlet ports 96 wh ch communlcate w1th a source ofc mpressed'air through a passage 24 and the sprin controlling valve 29 preponderate over the steam pressure exerted on diaphragm 22, the plunger 23 'wlllmove downwardly and the valve 29 will \close. This preponderance in ressure, however, cannot continue, since t e diaphragm 27 will move away-from the inner endpf the stem 31 and, establishing commumcation between the chamber 28 and the atmosphere, reduce the pressure within the chamber 28.

With such an arrangement of ap aratus, the pressure delivered to the cham er 28, and consequently to the relay control deyice 12, will be automaticall adjusted until equilibrium is establishe and the plunger 34 will therefore occupy defimte and determined ositions for different steam pressures ddlivered to the diaphra 22 of the device 10. The cam 38 will, t erefore, oc-

cupy definite positions for difierent steampressures encountered and consequently the re ay mechanisms will proportion the pressure of the air delivered by it in response to variations in the pressure of the steam within the pipe 11 Or the steam pipe communica' with the device 10.

In Fig. I have shown a hand lever 81, whichv is mounted on the cam shaft 41 and which may be employed in turmn the ca m to any desired position and locking It: in this position so as to relieve the mechanism 14 of the 'automatic'control of the device 12. With this arrangement, the mechanism 14 may be set to deliver any desired pressure, within possible limits, to the various control mechanisms, and this pressure wlll be maintained independently of variations in the steam pressure delivered by the steam generator or generators contro ed.

In Figs. 5 and 6, I have illustrated a modified form of apparatus, which may be employed for controlling the air pressure delivered to the control mechanisms 15 and 16. This mechanism may replace the devices 10 and 12 and the relay mechanism 14 of Fig. 1. Y

It includes a chamber 82, adapted to re ceive steam, through a passage 83, from a steam header or pipe communicating with the boiler. or boilers to be controlled. The chamber is provided w1th a flexlble wall or diaphragm 84, against the outer face of which aplunger 85 is pressed by means of an adjustable s ring 86. A- pilot piston 87 is located wit in a cylinder 88, with which the mechanism is provided, and is operatively connected .tothe plunger 85, by means of a piston rod 89, so that it moves with the plunger. The'cylinder 88 is provided atone end with an exhaust port 91, and near 1ts middle portion with a fluid derylinder 88'.

livery port 92, which ceminunicates, by means of passages 93, with the pressure chamber 94 of a relay 97 and a branch passage 97', and which are controlled b the iston 87. As illustrated, the piston'8 is ho low and is provided with radial passages 98, adapted to coiiperate with the port or ports 96 in admitting pressure to the cylinder. In the illustratlon, the upper end -of the pilot piston is provided mechanism 95.. The

cylinder is also prov1ded with one or morewith a passage 99, in open communication with its hollow interior and with the upper end of the cylinder 88, while'the lower end.

of the piston is provided with a valved passage adapted to establish communication -between the upper 'endof the cylinder and the exhaust port .91. The valve shown in thls passage 1s a ball valve 100 and is adapted to be unseated by an adjustable stationary pm 101, when the piston 87 moves downwardly past a determined position.

A drop of steam pressure in the line, communicating-with the passage 83, will permit the plunger to .move upwardly in res onse to the, ressure of the spring 86. I

ward pressure on the piston 87 and will finally augment the steam pressure, delivared to the chamber 82, to such an extent hat the diaphragm. 84, and consequently the plunger 85 will move to their normal position 1n opposltion to the spring pressure 86.

As soon as this occurs the piston 87, moving with the plunger, will cut ofl communi= cation between the passage 97 andthe interior of the cylinder 88 by closing the port or ports 96, consequently the counter-balanclng alr pressure delivered to the cylin der 88 will be retained within the cylinder.

.As before described, this pressure is trans,-

mitted to the chamber 94 of the relay device 95, through the passage 93, which is in open communication with the upper end of the It will be apparent that the degree of essure delivered to'the chamber 94, in response to a given variation in the pressure of the steam within the delivery assage 83 or chamber 82, will be determlned by the relative efiective areas of the piston 87 and the diaphragm 84. For example tive area is one-fourth the eifective area of the diaphragm 84, a'drop of one pound in the steam pressure in the chamber 82 will occaslon a four pound increase-of the r by so constructmg the piston 87 that its e ecpressure within the c linder. 88 above the pilot piston 87. In t is way, the plunger 85 and its accessories operate as a pressure I multiplying device.

An mcreasing pressure within .the chamber 94 deflects 12, diaphragm 102, which separates the chamber 94 from a chamber 103, formed within-the-casing of the mecha- 'nism 95. This chamber 103 communicates,

v communicates with the atmos here.

. valve like the valve 110 is provlded with an- "engaged by the stem 114 when the dia-.

by means of apassage 104, with a vent chamber 105 and also by means of a port 106, wit the mechanisms /and 16 to be controlled. The mechanism 95 -is alsp rovided with a pressure chamber 107, w ich communicates, by means of a passage 108, with the source of supply of a1 r under prespassage jecting stem 111, which is adapted to be engaged by a finger 112,"mounte d on the 102, and to thereby establish communication between .the chambers 107 and 103 by opening-the valve, when the diaphragm 102 deflects in response to a preponderating pressure within the chamber 94. The chamber 105 is provided with a.rel1ef valve 113, which is spring closed and which is adapted to controLthe communication between that chamber and event port w p ihch inwardly projecting stem 114, which is located on the opposite side of the diaphragm 102 from the valve 110, but is adapted to be phr agm deflects in response to a preponderatirlg pressurewithin the chamber 103.

ith th1s arrangement the pressure in the chamber103 will be automatically"adusted so that itisequal' to the pressure with- 1n the chamber 94. For example, a preponderance of pressure within the chamber 94 5 over that existing in the chamber. 103 will deflect the diaphragm 102, thereby opening ,the valve 110 and delivering air under pressure from the source of supply to the chamber' 103 and consequently to all of the passages and mechanisms communicating with the delivery passage 106. As, the pressure builds up within this chamber, the dia phra 102 will deflect toward its normal position and will eventuallly permit .;the valve 110 to. close. If, for" any reason,

sure in the chamber 94, the diaphragm 102, deflecting in response to the preponderance... of pressure within the chamber103, will open the relief valve 113 and exhaust the 'ezzcesspressure to the atmosphere. If,

during the operation of the apparatus, the .steaflt-jpressureto which the diaphragm 84 is subjected, increases to such an extent that it moves the plunger 85 and consequently the pilot piston 87 to open the valve 100, the pressure in the upper end of the cylinder 88 will be reduced until it, operating in conjunction with the steam pressure on the diaphragm 84, just counterbalances the pressure of the spring 86, when the diaphragm 84 is in the normal position. This will reduce the pressure within the chamber 94 consequently occasion a preponderance of pressure within the chamber 103. The diap ragm 102 deflecting in response to this preponderating pressure, will open the relief valve 113 and discharge air from the chamber 103, and its communicating passages, until the pressure in the chamber 103 e uals the pressure in the chamber 94.

In ig. 4, I have illustrated an arrangement of apparatus which may be employed, in connectlon with the apparatus illustrated :in Fig. 1, to replace the pressure controlled device 10. That device proportions the pressure of the actuating air delivered to the relay control device 12, in response to variations in, the pressure of the steam from .the generators controlled, whereas the apparatus'shown in Fig. 4 is adapted to admit be so adjusted that'the blower engines and the stoker engine will continue to operate while the steam pressure is normal, but at such speed that the steam pressure will merely be maintained but not be built up above'normal.

' Referring to Fig: 4, the device illustrated includes a casing116, provided with a cylinder 117, in which a plunger 118 operates, and a cylinder 119, in which a plunger 120 operates. The casmg also includes an exhaust chamber 121, which communicates with the atmosphere; a passage 122, adapted to communicate with the air delivery pipe 32 supplying air-to the device 12; and

, a 0142' 123, which communicates with one the pressure wlthm the chamber "103 buildslfehd up too fast so that it exceeds the presreceiveair under pressure through the pipe of the cylinder 119, and is-adapted to 30. The other. on of the cylinder 119 communicates with a reliefpassage 124, which is controlled by a valve 125, controlled in its operation by the plunger 118. p

The lunger 120 is constructed'to operate wit in the cylinder 119 so that air delivered through t e port 123 normally exerts pressure on ,both sides of the plunger for the purpose -of balancing it. This may be accomplished in any suitable manner and, as illustrated, a restricted port 120 in the plunger is provided for the pur ose of insuring the delivery of air to both sldes of the plunger. A spring 126 is located between one end of the cylinder 119 and the plunger and is adapted to normally force the plunger to one end of its stroke, in which a valve 127, secured to the plunger, establishes communication between the passage 122 and the atmosphere, or exhaust chamber 121.

The plunger 118 is forced against a diaphragm 128 by means of an adjustable spring 129, whlch surrounds the stem 130 of the plunger. The opposite side of the diaphragm 1s exposed to steam pressure delivered through the pipe 21 and this pressure consequently tends to deflect the diaphragm 128 and move the plunger in opposition to the pressure of'the spring 129. The stem 130 is so positioned, with relation to the valve 125, that when this takes place it opens the valve and exhausts one end of the cylinder 119 so that the plunger 120 moves, in response to the unbalanced air pressure exerted on it and in opposition to the spring 126, and thereby shifts the value 127 to such a position that air under full pressure is delivered from the cylinder 119 through the passage 122. It will, of course, be understood that the relief valve 125 is so proportioned that it is capable of discharging more air than can leak around the plunger 120 and that it will, therefore, maintain approximately atmospheric pressure in the end of the cylinder, communicating with the passage 124:, when it is opened.

The operation of the apparatus is as follows: When the steam pressure in the passage 11 is below normal or the determined pressure for which the spring 129 is adjusted, the plunger 118 will occupy such a position, with relation to the valve 125, that the valve will remain closed. The plunger 120 will, under such conditions, be subjected on both sides to the pressure of the air entering the port 123 and consequently will be held by the spring, 126 in the position shown 1n the drawing, in which the passage 122 and consequently the pipe 32 is placed in communication with the atmosphere by the valve 127. This, as above described, will permit the plunger 34 of the device 12 to move to vthe end of its stroke in response to the pressure of the spring 37 and will thereby cause the relay mechanism 14 to dehver full air pressure, through the pipe 17, to the various control mechanisms. en the steam pressure delivered through the p1 e 21 returns to normal or to the determined pressure for which the sprin 129 is ad usted, the diaphragm 128 will be eflected by it and will move the plunger 118 so that its stem 130 opens the valve 125. Under such conditions, the plunger 120, movingin response to unbalanced air pressure, will shut off communication between the passage 122 and the atmosphere, and will deliver air under full pressure to the passage 122. This will force the plunger 34 of the device 12 to its extreme position, in opposition to the pressure of the spring 37, and will therefore adjust the relay mechanism to deliver minimum pressure through the pipe 17 to the control mechanisms.

While I have illustrated and described but one embodiment of my invention, it will be apparent to those skilled in the art that various changes, modifications, substitutions and omissions may be made in the apparatus illustrated without departing from the spirit and scope of the invention, as set forth by the appended claims.

What I claim is:

1. In an apparatus of the character de scribed, a source of fluid under pressure, a plurality of controlled mechanisms, a relay mechanism for delivering actuating pressure fluid to said control mechanisms, and a relay control mechanism actuated by variations in the fluid pressure from the apparatus to be controlled for delivering actuating pressure fluid to the relay mechanism, means responsive to the pressure of the fluid delivered to the relay mechanism to increase the pressure of the actuating fluid delivered by said relay mechanism to the control mechanisms in response to a reduction in the fluid pressure from the apparatus to be controlled, and to decrease the pressure of the actuating fluid delivered by said relay mechanism in response to an increase in'the fluid pressure from the apparatus to be controlled.

2. A boiler control apparatus ccfmprising a source of fluid under ressure, means responsive to variations 1n the pressure of steam delivered by the boiler controlled for delivering actuatlng fluid under pressure from said source of fluid to a relay control device, a relay'control device receiving actuating pressure from said means, a relay mechanism controlled by said control device for delivering pressure fluid at an increasing pressure as the steam pressure decreases and for delivering pressure fluid at a decreasing pressure as the steam pressure increases, and means responsive to the pressure delivered by said relay for controlling the operating of said boiler. 3.

n combination in a boiler control apparatus, a fluid pressure actuated control mechanism for controllmg the operation of a boiler accessory, a relay mechanism for delivering actuating pressure to said mechamsm, means controlled by varlations in the steam pressure of the boiler controlled for controlling the operation of the relay and means responsive to variations in speed of the accessory for counterbalancing the actuating pressure.

4. In. combination in a boiler control apparatus, a fluid pressure actuated control mechanism for controlling the operation of a boiler accessory, a relay mechanism for delivering actuating pressure to said mechanism when the steam pressure of the boiler controlled decreases, means controlled by variations in the steam pressure for actuating said relay, and means responsive to a variation in speed of the accessory for counterbalancing the actuating pressure.

5. In a stoker control apparatus, a control mechanism for controlling the o eration of an engine driving a blower supp ying air to the stoker controlled, comprising a valve for delivering steam to the blower engine, a pressure actuated plunger for opening the valve, means subjected to the pressure of the fluid pumped by the blower controlled for opposm the movements of the plunger and for OlOSlIlg the valve, and means responsive to variations in the pressure of the steam generated for controlling the delivery of pressure to the plunger of said control mechanism.

6. In combination with a boiler to be controlled, a furnace, a blower for delivering forced draft to the furnace, anengine driving said blower, and means responsive to variations in the pressure of steam delivered by said boiler and to the pressure generated by the blower for controlling the operation of said engine. I v

7. In combination in a boiler control apparatus, a blower for delivering air to the furnace operating in conjunction with the boiler controlled, and means responsive to the pressure of the steam generated by the boiler controlled and reacted upon by the pressure generated by the blower for controlling the operation of the blower.

8. In combination with a boiler'to be controlled, a furnace, a device for controllin the draft delivered to the furnace, an

means responsive to variations in the pressure of the steam generated by the boiler and to variations in the pressure of the draft for controlling the operation of the draft controlling device.

9. In combination with a boiler and its cooperating stoker, a stoker control apparatus, comprising a blower for delivering forced draft to the stoker, an engine for driving the blower, an engine for dri' ing the stoker, means responsive to variations in the pressure of the steam generated and reacted upon by the pressure developed by the blower for controlling the operation of the drivingengine of the blower, and means for controlling the {peration of the stoker engine in response to variations in the steam pressure generated by the boiler.

10. In combination with a boiler and its stoker, a centrifugal governor for controlling the operation of the stoker, means for varying the effectiveness of the governor for stoker, fluid delivery means responsive to variations in pressure of the steamdelivered by the boiler controlled, means responsive to the pressure of the fluid delivered by said first mentioned means and adapted to deliver actuating fluid pressure to the control mechanism and for increasing the actuating pressure delivered as the steam pressure decreases, and decreasing the actuating pressure as the steam pressure increases.

In testimony whereof, I have hereunto subscribed my name this 30th day of October, 1915.

HERBERT T. HERB. 

